Computers may be able to handle vast amounts of data, but we still need designers to translate it into something humans can understand visually. In the past, it was up to the imagination and skill of the lone scholar or campaigner to find and display the meaning in their own data. In the process, they often produced a kind of art. These visual feasts are being celebrated in a new exhibition at The British Library in London, which shows how learning to visualise data helped shape science and society. Caroline Morley

In 1854, during an outbreak of cholera in central London, physician John Snow interviewed local residents to find out where people were sick, and then plotted the cases on a map of the area. He found a distinct cluster centred on a water pump on Broad Street (now Broadwick Street). The schematic below prompted the local council to disable the pump, simply by removing its handle. The move helped to end the epidemic. Snow correctly concluded that cholera is waterborne and not caused by bad air, as most people believed at the time.